Introduction: Computer Racks for Chromebooks, IPads
A few years ago I wrote an Instructable for creating an iPad or Chromebook Cart for School. It was made of wood, which raised concerns from readers about heat and fire (our tests showed no rise in temperature over three years of use, the last one with Chromebooks--it was well ventilated)--concerns our school's insurance carrier shared. I used wood because a) I have little metal work experience, b) the rack is difficult to make and design in metal, but easy in wood. Our admins made it go away.
It was replaced by a generic metal storage box from Staples. As in the original design, real laptop carts are expensive--to the tune of thousands of dollars. The boxes were fine. Our tech folks crammed power strips and power cords into the back, though, and zip tied everything together, but their solution for racks were dishwasher racks.
Typical of the IT admin mind-frame (i.e., not those who will use it daily) they were convinced that the dish rack would be sturdy and easy to use because a) they'd seen it suggested as a solution on the internet, b) one classroom somewhere in the district used them and "had no problem". That model classroom was small and the teacher stood by the cart while each third grader individually put their Chromebook in once a week. My classroom consists of fifty teenagers coming and going and dumping their Chromebook or pulling it out on the run. At the end of the day, half the Chromebooks were stacked to the side and, in the morning when a student would take theirs out, two others would come with it and crash to the ground. We needed something that could take a beating.
It had to be metal. It could not require welds. It needed to be sturdy. After a week of racking my brain (ha, ha) I had a flash of insight--oven racks. Now I was cooking (ha, ha).
Step 1: Materials
The materials are pretty basic.
Oven racks: You can get shiny new ones online pretty cheap, but with an email to my local waste disposal site (the dump) they easily put aside a half-dozen. As this was a prototype, the one in the photo was not well cleaned--you can do better!
License plates (2): Once the racks are bent, they need to be held up and attached to the base. In looking for a piece of metal that would do the job, I found license plates to be the perfect size. Unlike buying a piece of metal and cutting it down, the edges of a license plate are smooth and they look cool. Here in Vermont, people have them gathering dust in barns--supplies are free and plentiful.
Steel loop clamps (4): The rack has to be attached to the license plate without welds. I had tried the plastic loop clamps that are used to attach cords and cables to baseboards, but they snapped too easily. Not only was it much harder to even find the name of the thing I knew existed (loop clamp), but it was unclear the size of the loop vs. the size of the hold for the bolt (3/16) when ordering. From the photo above, you can tell the hole for the bolt is huge--nearly the size of the bolt head! I'm sure you can find smaller, but these worked (you can add washers if it's a problem). These clamps are from Amazon--I needed four, but a bag of 50 was cheap. I had thought any hardware store would have it piecemeal, but not around here (or Home Depot).
Bolts and Lock Nuts (8): I used 1/4" inch bolts 1/2" in length with locknuts, as the push-pull of use will loosen the nuts and it will fall apart before anyone will bother to tell you its going to break. Locknuts solve this.
Tools: Drill. 1/4" drill bit that drives through metal. Wrenches and socket set. Clamps.
Step 2: Bend the Rack
In order to keep the Chromebook or iPad vertical for charging there needs to be support at both ends of the device. To do this, the rack is bent at a V. Because the oven designers knew the rack was going to be abused and needed to maintain structural integrity through harsh conditions they put a reinforcing bar half way deep. That will be the fulcrum of our V.
To bend the rack uniformly, I used my workbench to counter the force I was going to use to bend it. The reinforcing bar is lined up on the edge. On the half of the rack laying on the bench, I placed a 2x6 board and clamped that down--that way, when I put force on the free end of the rack, the other end did not going anywhere.
Secured, push down on the free end carefully until it is at a right angle. Go slow.
As the individual bars within are thinner than the rack's outer frame, you will need to straighten them out individually to get a crisp angle. That can be done by hand.
You may have to readjust your angle. Take a device (Chromebook, iPad) and place it in the rack while you hold it at an angle manually. Does it fit? Bend the rack as needed to make it work. Once you get it right, you only need to secure it at that angle.
Note: One end of most oven racks have a little dip bend near the edge. In the photos, you might note that I bent that down, too (the opposite direction). It helped it fit in the box and (perhaps) offered a tiny extra stabilizing bit instead of just going off into the nether. Optional.
Note: Later, making more and in a hurry, I just put the rack on the floor, put my feet at the points I wanted to bend in the middle, and pulled up carefully. It's quick, but I noticed it was not perfect.
Step 3: Making Rack Supports
You are going to bend the license plate into an L for vertical support. The bend is about an inch from the long edge. In Vermont, they put a convenient white line at the bottom of the plate and I bent it there. Both racks should be bent at the same place, but will be mirrors of each other (if you care about the painted side showing).
The bending process is the same as the rack.
Like the rack, I shored up the bend by hand. Later, I also used the on-the-floor-using-my-feet trick when in a hurry, except it was hands and a workbench and not the floor and feet. But I have large hands and can manipulate it. Don't be afraid to use a hammer and the edge of your workbench to get that angle tight, but if you do hammer on the back so you don't mar the paint.
Step 4: Secure the Rack to the Stabilizers
You want the L of the license plate to face inward if you are putting this in a box--it saves space. The door to our metal box was about two inches wider than the rack; space was important.
Using a Chromebook, iPad or other desired device as a demo, configure the angle of the V and the pitch it will sit at. The angle needs to be steep enough so that the front and back of the V holds the device secure. If you pitch it too far either way, it will only be held on one end.
If you are putting this in an enclosed space be sure to test the space before drilling and securing. When I first did this, the front bar was so high that, when I secured it in the metal box, there was not enough clearance between the front edge of the rack and the top of the doorway. I couldn't get the Chromebook in. A half an hour was wasted redoing this step.
Once you have decided on the angle and pitch, mark how it will stand next to the license plate. Put the clamps on the rack itself--one that falls near the front of the license plate and one near the back--and mark where the clamp holes fall. Drill holes for the clamps. Screw it to the plate, heads on the inside so Chromebooks and hands don't get snagged on the bolt itself.
Test the device in it again. Does it stand secure? If not, redo it.
Step 5: Done
Now you have a rack.
If you decide to secure it to a counter or inside of a box, the license plates already have holes drilled in the feet. Just mark the hole nearest the front and drill into the surface. Bolt and lock it down--two bolts total did it for me.
Some schools put them in a closet they then lock. Others just leave them on a counter.
Because we had ten cords for each rack, we zip tied them in two bunches of five. Then, we hung them from above as it seemed to keep them from jamming in the door.
We have a be nice policy.
Please be positive and constructive.